Page 276 of AES Mastercatalog by Aquatic Eco-Systems

mechanical filtration filter media mixed media different grain sizes segregate solids throughout the bed mixed media filtration greatly surpasses the performance of single media filters the drawback to a single media filter is that the first one inch of media is trapping most of the solids and the bottom portion is just wasted space a sand filter that uses a single size sand grain will have an average size space between the grains that varies only slightly if that space were 400 microns on average the sand bed would probably have a nominal particle retention of 250 microns the dirtier it gets the better it filters because the spaces get plugged a mixed media filter uses different grain sizes to segregate solids throughout the bed a large media is used first to pre-filter large solids beneath that is a finer size and then a very fine media on the bottom each media used is a different specific gravity designed so that it will return to the ideal stratified layer after backwash during backwash the entire media bed is expanded fluidized and rinsed upon return to normal operation the media that is the smallest and heaviest settles first to the bottom the largest is the lightest and settles on top out in waste out in waste mixed media single media mm1 mixed media our mixed media contains 4 sizes of media that will greatly enhance a filter s performance reduce backflush frequency and prevent channeling the coarse top layer is carbonite with sizes between 2.0 and 2.2 mm this material can remove iron and manganese that adhere loosely to the angular carbonite particles and backwashes easily ratios of each media are based on years of use in other industries our media is premixed in 1 cubic foot containers which weigh approximately 80 pounds each the specific gravity of mixed media is between 1.6 and 4.2 sand is 2 to 2.8 so the backwash pressure or volume may have to be adjusted mm1 59.00 53.98/4 51.47/12 particles are captured throughout the mixed media filter instead of primarily on the top tech talk 43 sand filter media there are numerous choices of media for sand filter vessels other than sand for instance you can use plastic beads granular media of mixed size or lightweight filter media for particulate removal activated carbon can be useful for the removal of dissolved organics chlorine antibiotics ozone etc be sure care to replace carbon before it becomes saturated with the material it had previously adsorbed sand filters can also be used with zeolite which is an ionic exchange mineral with the ability to adsorb ammonium ions from fresh water regardless of the media chosen always backwash or rinse new material prior to operation to remove dust and fines that could irritate fish or cloud the water sand filter housings can also hold biofilter media and perform as pressurized biofilters this works well when using only one pump to cycle water from the culture tank through the filters to a height appropriate for spraying or degassing and then back filters can be put in series where two or more are used one for particulates one for dissolved organics one for biofiltration one for carbon etc be aware that the published maximum clean water flow rate through a sand filter is typically much too high for aquaculture sizing a flow rate less than half of the filter s maximum is what we recommend when selecting a vessel in aquaculture particular attention must be paid to backflushing frequency and volume recirculating aquaculture water s high organic content makes most media especially sand stick together and usually requires backwashing two or more times per day remember that sand filters are designed for sand media which has a small grain size and heavy specific gravity the use of any other media will require experimentation to find the best backflush water volume particulate removal down to the 20­40 micron range our lightweight media reduces the problem of backflush channeling a common problem with sand filters in reuse aquaculture this occurs when the heavy sand media doesn t fluff up bed expansion as it should because the organics and bacteria make it stick together our lightweight media minimizes the problem because it expands 30­50 percent with only 8­10 gpm per square foot backflush if the flowrate is in excess of 10 gpm per square foot of area a restricting valve on the backflush drain may be needed to prevent the loss of media weighs only 25 lbs/ft3 sand is about 100 lbs per cubic foot and comes in bags the irregular shape of the lightweight media provides more void space resulting in less pressure loss its irregular surface provides particulate removal down to the 20­40 micron range made of anhydrous silicon dioxide and approved for potable water try it depending on conditions it could solve your backflush channeling problem like it has for others wt each 5 lightweight sand filter media jf1 jf2 1 ft3 2 ft3 25 lbs 50 lbs 25 44 23 40 last fall i purchased a fb109 air pump from your company the reason for this letter is to let you know that i am very pleased with the product that i purchased from you at the time of our conversation we did not know what size of pump i would need to do the job i wanted to do i took a guess at the fb109 and it turned out to be an excellent choice i hooked up the pump to my 12 circle apparatuses and plugged it in about nov 06 [it s doing the job i was hoping it would do keeping my pond open for my swans to have water there was a couple of cold days where the hole froze completely over but when the cold snap broke the air system again opened the hole i will be taking the system out in about 2 weeks i also did not lose any fish this winter again i would like to say i am very pleased with your product and would highly recommend your product to any one who is also thinking of doing the same thing i did sincerely yours wayne copland order online aquaticeco.com order by phone 877-347-4788 tech support 407-598-1401 273

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